Last week, news broke that the Justice Department obtained records from AP for its investigation into an internal leak. Now, details are emerging about an investigation of a Fox News reporter that some experts say could harm investigative journalism even more.

Attorney General Eric Holder testifies before the House Judiciary Committee on Capitol Hill in Washington Wednesday. Holder told the committee that a serious national security leak required the secret gathering of telephone records at The Associated Press.

This time, it’s new details about a 2010 Justice Department investigation into a Fox News correspondent who reported government secrets on North Korea. The twist is that in the Fox News case, the government is suggesting that the reporter broke the law and criminal charges could result.

The news points to how the Obama administration is going to unprecedented lengths to defend secrets – prosecuting more government leakers under the 1917 Espionage Act than all prior administrations combined.

Anecdotal evidence suggests the crackdown is having an effect, with AP saying some of its sources are falling silent. But that success could come at the expense of the newsgathering and investigative-reporting process that the Founding Fathers saw as a crucial check on federal power.

The Fox News case, in particular, suggests the “criminalization of investigative journalism,” writes Glenn Greenwald in The Guardian, a British newspaper.

According to a Washington Postreport Sunday, Fox News chief Washington correspondent James Rosen reported in June 2009 on a CIA analysis that suggested North Korea may respond to UN sanctions with more nuclear tests. The story was published online the same day that a confidential report on the matter was released to select officials in the intelligence community, including a State Department security adviser, Stephen Jin-Woo Kim.

Detecting a connection, FBI investigators built a case alleging Mr. Kim leaked information to Mr. Rosen. To do so, they used every tool in their arsenal: analyzing security badge access records to track Rosen’s comings and goings from the State Department, tracing the timing of his calls to Kim, even subpoenaing his personal e-mails.

Ultimately, FBI agents concluded Kim did, in fact, leak information to Rosen using a complex, if clumsy, system of communication including aliases and coded signals.

In his report, FBI investigator Reginald Reyes said evidence suggested Rosen had broken the law, “at the very least, either as an aider, abettor and/or co-conspirator.”

While details on the case are forthcoming, it is not a crime for journalists to report classified information, except in rare circumstances. Furthermore, government seizure of media records is tightly circumscribed under the government’s Code of Federal Regulations.

The AP and Fox News cases renew concerns about the potential stifling effect government investigations have on reporters and their sources.

“Search warrants like these have a severe chilling effect on the free flow of important information to the public,” said First Amendment lawyer Charles Tobin in the Washington Post report. “That’s a very dangerous road to go down.”

Jane Mayer of The New Yorker goes further: “It's a huge impediment to reporting, and so chilling isn't quite strong enough, it's more like freezing the whole process into a standstill,” she told the New Republic.

“Already, officials that would normally talk to us and people we talk to in the normal course of news gathering are already saying to us that they're a little reluctant to talk to us,” he said. “They fear that they – they will be monitored by the government.”

Perhaps the most serious implication, however, is that the investigations threaten to jeopardize the very practice of investigative journalism, already endangered by budget cuts and the 24/7 news cycle.

“Under US law, it is not illegal to publish classified information,” writes The Guardian's Mr. Greenwald. “That fact, along with the First Amendment's guarantee of press freedoms, is what has prevented the US government from ever prosecuting journalists for reporting on what the US government does in secret. This newfound theory of the Obama DOJ – that a journalist can be guilty of crimes for 'soliciting' the disclosure of classified information – is a means for circumventing those safeguards and criminalizing the act of investigative journalism itself.”